Theftproof light bulbs



July 8, 1958 M. H. JACOBS THEFTPROOF LIGHT BULBS Filed June 11, 1954 FIG.

FIG. 7

INVENTOR MILES H. JACOBS ATTORNEY United States Patent THEFTPROOF LIGHT BULBS Miles H. Jacobs, Malta, Ohio Application June 11, 1954, Serial No. 435,996

3 Claims. (Cl. 313-318) This invention relates to non-reusable light bulbs, and has for its object to provide a light bulb of this type which is inexpensive, and positive in operation.

A further object of my invention is to provide a light bulb of the type described which can be used in any standard socket.

A still further object of my invention is to provide a device as described which is similar in appearance to the regular bulb.

A furtherobject of my invention is to provide a light bulb which if stolen from a light socket, will automatically become permanently inoperative.

Other and further objects will be apparent from the following specification and claims.

In the drawings:

Figure l is an elevational view of the light bulb as it appears ready for use.

Figure 2 is an enlarged cross sectional view of the base of the bulb, showing the mechanism in the position it occupies before the bulb is screwed into a socket.

Figure 3 is a view similar to Figure 2, but with the bulb screwed into a socket.

Figure 4 is a cross-sectional view of the base taken on line 4-4 of Figure 2.

Figure 5 is a cross-sectional view of the base taken on line 55 of Figure 3.

Figure 6 is a cross section of the base with the operating mechanism removed.

Figure 7 is a top plan view of the arm showing it in engagement with the cutaway portion on the shaft.

Referring to the drawings in detail, numeral 10 represents a glass bulb or envelope having a threaded metal base 11 secured thereto by any suitable means. Inside the base 11 is a cup shaped housing 12 of non-conductive material having a bore 13 through its lower portion. A non-conductive binding material 14 forms a cover for the open upper portion of the housing 12, and encloses the bent over portion 15 of the threaded base 11. Aligned with the bore 13 in the housing 12 is a larger bore 16 in the material 14. Within said bore 16 is a bushing 17, having a bore 18 therein of the same diameter as bore 13 and aligned therewith. The bushing 17 is preferably made of non-conductive material. A shaft 19 having a reduced portion 19A has a contact arm 20 freely rotatable on said reduced portion, and is mounted for reciprocation within bores 13 and 18. A coil. spring 21 having ends 22 and 23 encircles shaft 19, the end 23 engaging the contact arm 20 and the end 22 being attached to the lower portion of the housing 12. The spring thus exerts a continual upward tension on the shaft 19 as well as a continual rotary tension on the contact arm 20, this tension being shown as exerting a counter-clockwise movement to the arm 20 in Figures 4 and 5. On the inner wall of the housing 12 is an arcuate member 24 having depending stops 25 and 26, said member and stops being of non-conductive material and either integral with said housing or attached thereto. A stop 27 of conductive 10 situated in the positions shown in Figures 2 and 4. The

2,842,700 Patented July 8, 1958 ice , envelope 10. A binding material 32 of a ceramic or other suitable material is placed between the portion 31 of the glass envelope and the lower portion of the housing 12.

The operation of the device is as follows: Before the bulb has been used, the respective parts are arm 20 is held against the lower horizontal portion of arcuate member 24 and against the vertical portion of stops 25 by the double action of spring 21 acting against the arm 20. As the bulb is screwed in a standard light socket the shaft 19 will gradually be forced inward overcoming the outward tension of spring 21 which has been keeping the arm 20 behind stop 25. As the bulb reaches its fully inserted position in the socket, the shaft 19 will be forced inwardly by the base of the socket and the arm 20 will clear the lower end of stop 25. When the arm 20 has cleared the stop 25, the spring 21 which is constantly exerting a counter-clockwise force on the arm 20 (as shown in Figure 4), drives the arm 20 against the conductive stop 27, which completes the circuit, and lights the bulb. The circuit is completed from the base of the socket, thru the shaft 19, the arm 20, the stop 27, the filament wire 28, the filament (not shown), the second filament wire 30, the screw base 11 and the mating screw wall of the socket.

As long as the bulb is left undisturbed in the socket, the bulb will continue to burn until the filament burns out as in standard lamps. If, however, a thief removes the bulb from the socket, the spring 21 will cause the shaft 19 to move outwardly, and when the bulb is nearly out of the socket, the arm 20 will clear the top portion of the stop 27 and rotate counter-clockwise (as shown in Figure 5), until it reaches the non-conductive stop 26. The bulb will thus be rendered permanently inoperative, as the spring 21 will hold against the stop 26, no matter how the bulb is manipulated.

What is claimed is:

1. A theftproof light bulb comprising a glass bulb having the usual filament therein, a screw threaded base portion on said bulb having a filament wire attached thereto, a housing in said base having a contact member thereon, the other filament wire attached to said contact member, said housing having a cover thereon, a spring tension shaft reciprocably and rotatably mounted in said housing and said cover and having contact means thereon adapted to engage the contact means in said housing when said bulb is inserted in a socket depressing said spring tensioned shaft.

2. A theft proof light bulb comprising a glass bulb having the usual filament, a screw threaded base portion having a non-conductive bushing on said bulb, a housing in said base portion, a filament wire connected to said screw threaded base, a housing in said screw threaded base, contact means in said housing, a filament wire connected to said contact means in said housing, spring tensioned means reciprocally and rotatably mounted in said housing and said conductive bushing in said cover, contact means carried by the spring tensioned means adapted to engage the control means in said housing 3 4 housing in said screw threaded base, a filament wire con- References Cited in the file of this patent nested to said screw threaded base, contact means in UNITED STATES PATENTS said housing connected to a filament wire, means in 603 705 Phl said housing supporting a contact means adapted to en- 1 368370 T 2 2 1898 gage the contact means in said housing to complete a 5 1575992 ga 3 1921 circuit when said light bulb is inserted in a socket and 1724654 g i Z t b v 7 o permanently reak a circuit when sa d bulb 1s removed 1,753,609 Korte et aL APR 8, 1930 mm 1,914,702 Peth June 20, 1933 

